Drepana arcuata

The Drepaninae are the hook-tip moths, named for the characteristic wing-shape. This species is double brooded, so that caterpillars found early in the summer will produce adults later in the year, whereas caterpillars found in late summer will pupate for the winter. The caterpillars are distinctive in that they have no anal claspers, but the last segment is drawn out into a hard point. The caterpillar often assumes a dragonlike posture with head and tail up, standing on its abdominal prolegs. It rests on the surface of an alder leaf under a silken roof which it has built for itself. I have often noticed the caterpillar jerking its head up and down making an audible "tic-tic" sound. The several different sounds made by hook-tip caterpillars, how they are made, and the significance of these sounds (some of which appear to be territorial warnings to other caterpillars - "Stay off my leaf!"), have been studied by Dr Jayne Yack of Cornell University. This work has been described, for example (and presumably elsewhere!), in an article by Cora Lee in the Jan/Feb, 2002, issue of the fine children's magazine Yes Mag (www.yesmag.ca).